INTEGRATED CAPILLARY ELECTROPHORESIS ON FLEXIBLE SILICONE MICRODEVICES - ANALYSIS OF DNA RESTRICTION FRAGMENTS AND DETECTION OF SINGLE DNA-MOLECULES ON MICROCHIPS

Microchips for integrated capillary electrophoresis systems were produ ced by molding a poly(dimethylsiloxane) (PDMS) silicone elastomer agai nst a microfabricated master. The good adhesion of the PDMS devices on clean planar surfaces allows for a simple and inexpensive generation of networks of sealed microchannels, thus removing the constraints of elaborate bonding procedures, The performance of the devices is demons trated with both fast separations of phi X-174/HaeIII DNA restriction fragments labelled with the intercalating dye YOYO-1 and fluorescently labelled peptides, Detection limits in the order of a few zeptomoles (10(-21) mel) have been achieved for each injected DNA fragment, corre sponding to a mass detection limit of similar to 2 fg for the 603 base pair fragment. Single lambda-DNA molecules intercalated with YOYO-1 a t a base pair-to-dye ratio of 10:1 could be detected with an uncomplic ated laser-induced fluorescence detection setup, High single-molecule detection efficiency (>50%) was achieved under electrophoretically con trolled mass transport conditions in PDMS microchannels.